IMSK - Exam 1

What does a lameness exam consit of

Musculoskeletal palpation and stand back and look at the horse
Dynamic exam - Flexions, blocking
Imaging

What are you evalating on the musculoskeletal palpation of an equine lameness exam

Areas of sensitivity and heat, obvious soft tissue swelling, joint effusion
Assymmetry in pain, effusion, swelling/thickkening

Hoof tester test for hoof sensation and pain in the

wall, sole, frog, heel bulbs

Canter/Lope

Rocking type motion through hindend then forehand
If turing, inside HL and inside FL should land first

Gaiting

Four beat gaits with the same pattern as walk
A really fast walk

Steps to a dynamic exam

1) Is horse lame or sound
2) If lame, is horse lame in forelimb, hindend or both
3) Which limbs are lame
4) Grade the lameness in each limb

Forelimb lameness - what happens to cause the signs we see

Pain → decreased load → Decreased flexion → decreased decent of trunk

How to tell whcih leg is lame in equine lamenss

Forelimb - down on sound
Hindlimb - increased gluteal excursion (hip drop or hip hike)

Lamness exam at a lunge line - signs of lameness

Can exacerbate the lameness, shortened cranial phase of the stride, axial placement of the hind limb, slow to advance the hindlimb, reduced stance duration

Signs of lamness at the canter

Lack of dissociation of the hindlimbs, lack of flexion through lumbosacral region, incorrect lead

Sings of lameness - Attitude

Reluctance to go forward, head shaking/tail swishing

Grading lameness: Equine AAEP scale

5- non weightbearing lame
4- Lame at the walk
3- consistiently lame at the trot under all circumstances
2 - consisitently lame at the trot under certain circumstances
1 - inconsistently lame at the trot under certain circumstances

Equine Bilateral leameness can be hard to detect so look for

Short, choppy, or shuffling gait

Flexion Tests - Distal limb

Stresses fetlock, pastern, coffin joints

Flexion Test - proximal hind limb

Stresses stiffle, lumbar back, SI

Flexion Test - Full limb hind

Stresses all joints in the hindlimb except hock/proximal metatarsus region not stressed with other hindlimb flexions

Ridden exam for lameness Exam

performed for subtle lameness or ones that occurs only during a certain movement, lameness that the rider can feel

Diagnositc Analgesia Contraindications

Local inflammation, cellulitis, dermatitis
Suspcion of a fracture - recent severe lameness, incomplete fracture
Laminits - ok for diagnosis but not repeated injections

Peri-neural nerve blocks start where and move where and how to give

Start nerve blocks distally and move proximally
(nerves are continuos)
Aim needle distally when possible
low volume as possible
Look at horse soon after performing block

What drug do you use for blocking equine and it’s method of action

Carbocaine
Blocks Na channels and prevents depolarization of membranes (blocks nerve conduction)

Forelimb Lameness nerve blocks

Palmar digital nerve block
Basi-sesamoid/abaxial nevrve block
Low - 4 point nerve block

High 4 point nerve block
Deep branch of the lateral palmar nerve/lateral palmar
Median/ulnar

Hindlimb nerve nerve block

Abaxial nerve block
low -4 point nerve block

Deep branch of the lateral plantar nerve
Tibial/peroneal

Mjority of forelimb lameness or _____ while hindlimbs are

Forlimb - fetlock down
Hindlimb can be anywhere as hock and stifle pain is common

Palmar Digital Nerve Block “Heel Block” - location, drugs, needle

Palpable neruvovascular bundle, abaxial to flexor tendon sheath, proximal to collateral cartilages
1.5-2 ml carbocain
25 gauge 5/8” needle

Palmar Digital nerve block - what structres are desensitized

“The heel”
Digital Cushion
Navicular bone
Navicular bursa
Distal aspect of the deep digital flexor tendon
Entire sole/frog
Impar ligament
Palmar aspect of the distal interphalangela joint

Basi-sesamoid/Abaxial nerve block - location, durgs, needle

Base of sesamoid vs body of sesamoid
1.5 - 2.0 ml carbocain
Limb up or down
25 gauge 5/8” needle

Basi-sesamoid/Abaxial nerve block - what nerve

Palmar digital nerves (M&L)

Basi-sesamoid/Abaxial nerve block - what are desensitized

All in the lower palmar digital nerve block
Entire distal phalangeal joint
Entire proximal interphalangeal joint
Dorsal hoof wall
Superficial digital flexor tendon within the pastern region
Deep digital felxor tendon within the pastern region
Straight sesamoidean ligament
OBlique sesamoidean ligaments
Collateral ligaments of the distal interphalangeal joint
May block a portion of the metacarpophalangeal joint

Low 4-point nerve block - what enerves

1) Lateral palmar nerve
2) medial palmar nerve
3) lateral palmar metacarpal nerve
4) Medical palmar metacarpal nerve

Low 4-point nerve block - landmarks, needle, drug

Aseptic preparation
25 gauge 5/8'“ needle
2-3 mL carbocaine per site
Alternative for palmar nerves, 22 gauge 1.5” single needle stick (more likely to enter tendon sheath)

Low 4-point nerve block - close strucutres

MCP/MTP joint
Digital flexor tendon sheath (DFTS)

Low 4-point nerve block - what is desensitized

All in basisesamoid nerve block
Entire metacarpo(taso)phalangeal joint
Suspensory branches
Supperfiical digital flexor tendon within the distal metacarpus (tarsus)
Deep digital flexor tendon within the distal metacarpus (tarsus)
May block a portion of the proximal suspensory ligament

Peri-neaurl vs Intra-synovial

Peri-neural is easier with less risk but is less specific and used for the distal limb below the carpus/tarsus
Intra-synovial is a better assessment of proximal limb

Complications of peri-neural anesthesia

Hematoma - low 4 point, bandage
Needle breakage
Celluitis - bandage, antibiotics/anti-inflammatories
Intra-synovial injeciton - aseptic prep

Complications of intra-synovial injecitons

Needle breakage - small needles with high motion joints
Joint flare - acute inflammatory response (24 hrs after)
Synovial infection (7-10 days after)

Radiogrpahs and MRI have limited ____ skeleton imaging so instead you should use

axial, use CT

Cons of Ct in equine

Expesnive, hospital procedure and many unit srequire general anesthesia

MRI in equines can be used to dx what problems

Cartilage damage
Soft tissue injuries within hoof capsule
Bone edema

Bone scans pros and cons

Lameness loclaizaiton adn the horse is standing but tells you where the problem is and not what it is, espensive ish and cna have negative/vauge results

Pet scan pros and cons

Funcitonal assessment of tissues, done standing, differentiate between active and inactive lession
In hospital, expensive, better if paired with other advanced imaging, no axial skeleton

For lameness localization, perineural blocks are started ____, working ____

Start distal and work proximally

Roles of muscle

Dynamic motion, stabilization, postural stability/balance

Motor unit

Alpha-motor neuron and skeletal muscle fibers

Concentric muslc econtraction

Muslce lenght shortens as it activates

Eccentric muscle contraction

Muscle lenght lengthens as it activates

Isometric muscle contractions

Muscle lenght stays the same as it activates

Muslce fiber types - Type I

Slow twitch
lots of capillaries and high oxidative capcity, slow repetitive movemtns, isometric forces, not power generatios, postural muscles

Muscle fiber types - Type II

Fast twitch
Low oxidative capacity, power generators
Large msucle with greater dynamic motion
IIA - some oxidative capacity
IIX - very low oxidative capacity but able to maximally shorten

During exercise fibers are recurited in order as intestivity and durations icnreases from

I, IIA, IIX

Equine sacrocaudalis dorsalits muscle is what muscle fiber type

Type I

Equine gluteal msucle adn semitendinosus are what muscle fiber type

Type II

Muscle spindle cell

In muscle belly, detects too mcuh stretch adn initiates reflex muscle contractions

Giolgi tendon organ

At the msuculotendinous junciton and detects too much contraction and intiates reflex muscle relaxation

Muslce damage pathophysiology

Cell damage allows Ca to enter the cytoplasm, activates destructive cellular proteases and inhibtis mutochondrial repsiration and reuslts in necrotic cell death → inflammaotry responses

Muscle healing steps

Ruptured myofibers retract forming gap between stemps (access for inflammatory cells from capillaries)
Contraction bands (cytoskeletal and sarcomeric material) plugs myofiber stumps, preventing further damage
Satellite cells (adult skeletal muscle stem cells) get activated nd migate to area of damage over 5 days and fuse to form multinucleated myotubes
Myotubes differentiate in myofibers (months)
If basmeement membrane damage occurs more extensive fibrosis cna ocur

How long does muscle healing take

4-6 and if extensive scar tissue is present a mechanical restriciton can occur

Clinical signs of myopathy

Stiffness, muscle hypertonicity/swelling, pain on muscle palpation, reduction in performance, unwilingness to work

Muscle strains/tears S/S

Hot, painful on palpation, swollen, lameness

How to Dx a muscle strain/tear

Ultrasound

7 basic gait patterns for dogs

Symmetrical - walk, amble, trot, pace
Asymmetrical - canter, transverse gallop, rotary gallop

Symmetrical gait

Limb movement on one side of the body is repeated on the opposite side

Diagonal gait vs lateral giat

Diagoal - the diagonal limb pairs move simultaneously
Lateral - the ipsilateral limb pairs move simultaneously

Stance vs swing phase of gait

Stance - when the limb is in contact with the ground
Swing phase - when the limb is in the air and advancing toward the next stance phase

What is the easiest gait to assess lameness

Trot

What gait can indicate pathology and when is it not

Pace
Normal for working dogs

Thoracic limb lameness is assessed at the _____ and what do you look for

Assessment at trot
Vertical head movments - down on the sound

Pelvic limb lamenes is assesed at the ___ and look for

At trot
Head raises when the nonaffected pelvic limb touches the ground
Hip hike or pelvic hike - pelvis elevated on affected side

Orthopedic Exam - standing palpation what do you look for vs recumbent

Standing - Symmetry, angulation and rotation, alignment
Recumbent - isolating joints

Musculokseletal palpation should begin at the ____ and joints should be ___. Do not forget about ____ and _____

beging at the toes and joints should be isolated
Do not forget about nails and paw pads

CREPI stands for

Crepitus
Range of motion
Effusion
pain
instability

Effusion is easier to palpate in joints with

less soft tissue coverage

Paw exam

Check naisl and pads, palpate every bone, manipulate joint and assess each for pain

Carpus exam

effusion - often palpated on the dorsal aspect of the carpus
Pain during ROM
Instability

Elbow exam

Palpate for effusion - palpated caudally from the epicondyle to the olecranon
During ROM feel for crepitus
pain upon full extension
pressure across epicondyle

Shoulder Exam

Palpate greater tubercle and acromion - effusion may be more difficult to palpate due to soft tissues
Palpate bicipital tendon
Extend shoulder
DO NOT FORGET to check the axillary region for pain masses etc

Tarsus exam

Effusion - palpated dorsally and cuadally (betwen calcaneous and tibia)
Pain during ROM
Instability

Stifle exam

Effusion - Palpate the medial aspect of the patellar tendon
Periarticular enlargement
Palpate for patellar luxation
tibial tuberosity is your HOME BASE

Hip Exam

Through ROM, have finger lightly on greater trochanter
Be sure to extend and abduct/adduct the limb
Ortilani sign
Palpate pelvic trianlge

Elasticity

Ability to return toward original shape after load removed

Bone biomechanics directly influences

how fractures occur, how we repair them, and how they heal

Bone multicellular unit consits of

Bone cells (2%) and extracellular matrix (Type I collagen 95%, osteoid, hydroxyapatite)

Osteoblasts function

Growth, produce new bone matrix

Osteocyte function

Maintenance

Osteolast function

resorption

Bones
Load →

load → Elastic → yield → plastic → fracture

Wolff’s Law

Bone remodels in response to mechanical loads place upon it
It remodels with use or diuse

Direct bone healing

Facilitated by facture compression that leads to a gap under 0.01mm
Little to no callus

Secondary bone healin

Instability and/or gap over 1mm
Callus

Bone repair soft callus is mainly made of

type III collagen

Fractures are at their weakest at

2 weeks pos injury

Bone is or isn’t inert

Bone is not inert

Bone modeling and remodeling are the same or differet

Distinct processes

what induces bone adaptation

Strain especially strain magnitude

What controls progression of fracture healing

Strain

Bone can heal to ____% strength and has the potential to ______ but this can be prevented by

100% strength and the potential to fully regenerate
Instability, infeciton, metabolic abnormalities, bone gaps

Bone heal can or can’t be accelerated

Accelerated

Desmopathy

Pathology of a ligament

Intrinsic healing

Cells and vascular supply within the tendon contribute to repair
Generally greater supply at the periphery

Extrinsic healing

Blood comes from outside the tendon (muscle, bone, accesory ligaments) and into the surrounding tissues contribute cells and blood supply

Fibroblast cells are arrange accoring to

the mechanical environment of the tissue